1. Field of the Invention
This invention generally relates to airpot beverage dispensers and methods of serving beverages, such as freshly brewed coffee, iced tea, lemonade, ice water, hot water and the like, from airpot beverage dispensers.
2. Discussion of the Prior Art
Airpot beverage dispensers of the type that have a insulated hollow body for storage of beverage and a pressurization system for forcing beverage to travel up a feed tube within the hollow body to a spout at the end of an open feed tube outside of the hollow body. Typically, the bellows is mounted within a cover assembly to which is also movably mounted a bellows actuator in the form of a pivotally attached lever or a push button that pushes on the top of a bellows to force air into the hollow body. When the bellows is actuated, the pressure within the hollow body is increased relative to atmospheric pressure and this pressure differential forces the beverage up the feed tube and out of the spout. The liquid contents are displaced with pressurized atmospheric air. Examples of airpot dispensers are shown in U.S. Pat. Nos. 4,290,537 issued Sep. 22, 1981 to Chi-Jung; 5,156,297 issued Oct. 20, 1992 to Engler and 5,887,760 issued Mar. 30, 1999 to Johnson.
A relative advantage of this airpot design is that the spout is located adjacent the top to enable the location of a coffee cup, carafe or the like beneath the spout without the need to support the bottom of the hollow body above the underlying support counter. Such support is required with beverage dispensers having a gravity feed faucet located at the bottom of the hollow body. Both gravity-feed faucet type beverage dispensers and airpot dispensers both have the advantage of not requiring the entire hollow body to be lifted and tipped to pour beverage from the top of the hollow body. In both types of dispensers, the contents are prevented from developing temperature equilibrium with the ambient air and resultant degradation of the beverage by means of insulation
The inventors have determined that there are two basic problems with current airpot designs. First, in all known airpot dispensers the cover that contains the bellows and carries the bellows actuator have no beverage inlets. Accordingly, the covers are designed to be movably mounted or removably mounted to the hollow bodies to enable passing beverage into hollow body through the entire uncovered open top of the hollow body. This may be done by pouring the beverage into the open top or by locating the open top beneath a faucet of a larger beverage dispenser or by locating the entire open top beneath a beverage outlet of a beverage brewer such as a fresh coffee brewer for direct brewing in to the top. This disadvantageously results in wide contact of the beverage with the room temperature ambient air and excessive loss of heat from within the hollow body by upward air convection, loss of steam and unreflected infrared radiation from the beverage flowing through the open top. This substantial heat loss continues throughout the period of filling the hollow dispenser. The filling period, in the case of filling directly from a brewer, may take 2-4 minutes, and heat loss continues thereafter until the cover of the dispenser is moved to a closed position or, if separated, is reattached to the hollow body.
In known insulated beverage dispensers of the type that drain beverage from a faucet at the bottom of an elevated hollow body, this problem of heat loss during the filing process has been reduced. In such case, in which the covers have no bellows blocking passage between the top of the cover and the interior of the hollow body, heat loss is reduced during the filling period by providing a fixedly mounted insulated cover with a relatively small inlet opening that may interface closely with a beverage outlet of a beverage brewer. However, because of known bellows designs, this approach has never been applied to air pots.
The other problem with known airpot dispensers is that they lack any reliable and hygienic means for determining the amount of beverage remaining in the airpot hollow body after serving has commenced. The insulated hollow bodies are insulated and are opaque and thus the level of the beverage within the hollow body is not visible from outside the body. In known airpot dispensers that are commercially available, the only way to determine the level of beverage within the hollow body is to open or remove the cover and look down into the open top of the insulated hollow body. Disadvantageously, this results in substantial heat loss through the open top and a resultant reduction in the serving temperature of the beverage, as explained above.
In the aforementioned U.S. Pat. No. 4,290,537 of Chi-Jung a mechanical float mounted for movement within the hollow body is mechanically linked to a level indicator, but in addition to being mechanical, the mechanical display of level faces upwardly only and disadvantageously cannot be seen from the side and thus cannot be seen from any significant distance. Similarly, a mechanical thermometer display is only located on the cap and only faces upwardly. In addition, the thermometer only measures the temperature of the steam within the hollow body above the surface of the beverage and does the actually directly measure the temperature of the beverage, itself. Moreover, undesirably, the cover is designed to be moved to enable filling of the hollow body through its open top and movement can only result in possible damage to the mechanical measuring devices and can only contribute to their inherent unreliability due to mechanical wear and tear.